[Xen-devel] [PATCH] tools: Fix wild memory allocations from c/s 250f0b4 and 85d78b4

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

These changesets cause the respective libxc functions to unconditonally
dereference their max_cpus/nodes parameters as part of initial memory
allocations.  It will fail at obtaining the correct number of cpus/nodes from
Xen, as the guest handles will not be NULL.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

---
Spotted by XenServers Coverity run.
---
 tools/libxl/libxl.c               |    4 ++--
 tools/misc/xenpm.c                |    4 ++--
 tools/python/xen/lowlevel/xc/xc.c |    4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index a6eb2df..295877b 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5105,7 +5105,7 @@ libxl_cputopology *libxl_get_cpu_topology(libxl_ctx *ctx, 
int *nb_cpu_out)
     xc_cputopo_t *cputopo;
     libxl_cputopology *ret = NULL;
     int i;
-    unsigned num_cpus;
+    unsigned num_cpus = 0;
 
     /* Setting buffer to NULL makes the call return number of CPUs */
     if (xc_cputopoinfo(ctx->xch, &num_cpus, NULL))
@@ -5191,7 +5191,7 @@ libxl_numainfo *libxl_get_numainfo(libxl_ctx *ctx, int 
*nr)
     uint32_t *distance;
     libxl_numainfo *ret = NULL;
     int i, j;
-    unsigned num_nodes;
+    unsigned num_nodes = 0;
 
     if (xc_numainfo(ctx->xch, &num_nodes, NULL, NULL)) {
         LOGE(ERROR, "Unable to determine number of nodes");
diff --git a/tools/misc/xenpm.c b/tools/misc/xenpm.c
index fe2c001..2f9bd8e 100644
--- a/tools/misc/xenpm.c
+++ b/tools/misc/xenpm.c
@@ -356,7 +356,7 @@ static void signal_int_handler(int signo)
     struct timeval tv;
     int cx_cap = 0, px_cap = 0;
     xc_cputopo_t *cputopo = NULL;
-    unsigned max_cpus;
+    unsigned max_cpus = 0;
 
     if ( xc_cputopoinfo(xc_handle, &max_cpus, NULL) != 0 )
     {
@@ -961,7 +961,7 @@ void scaling_governor_func(int argc, char *argv[])
 void cpu_topology_func(int argc, char *argv[])
 {
     xc_cputopo_t *cputopo = NULL;
-    unsigned max_cpus;
+    unsigned max_cpus = 0;
     int i, rc;
 
     if ( xc_cputopoinfo(xc_handle, &max_cpus, NULL) != 0 )
diff --git a/tools/python/xen/lowlevel/xc/xc.c 
b/tools/python/xen/lowlevel/xc/xc.c
index fbd93db..c77e15b 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -1221,7 +1221,7 @@ static PyObject *pyxc_getcpuinfo(XcObject *self, PyObject 
*args, PyObject *kwds)
 static PyObject *pyxc_topologyinfo(XcObject *self)
 {
     xc_cputopo_t *cputopo = NULL;
-    unsigned i, num_cpus;
+    unsigned i, num_cpus = 0;
     PyObject *ret_obj = NULL;
     PyObject *cpu_to_core_obj, *cpu_to_socket_obj, *cpu_to_node_obj;
 
@@ -1293,7 +1293,7 @@ static PyObject *pyxc_topologyinfo(XcObject *self)
 
 static PyObject *pyxc_numainfo(XcObject *self)
 {
-    unsigned i, j, num_nodes;
+    unsigned i, j, num_nodes = 0;
     uint64_t free_heap;
     PyObject *ret_obj = NULL, *node_to_node_dist_list_obj;
     PyObject *node_to_memsize_obj, *node_to_memfree_obj;
-- 
1.7.10.4


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